Field of the Invention
The present invention relates to a scanning method and apparatus of a station (STA) and, more particularly, to a method and apparatus for performing active scanning by a STA.
Related Art
Recently, wireless LAN technologies have evolved in three directions. IEEE (institute of electrical and electronic engineers) 802.11ac and IEEE 802.11ad, as an extension of an existing WLAN evolutional direction, were released to promote a transfer rate. IEEE 802.11ad is a WLAN technology using a 60 GHz band. Also, a wide area WLAN utilizing a frequency band less than 1 GHz has recently emerged to allow for wide area transmission in terms of distance, relative to the existing WLAN. The wide area WLAN includes IEEE 802.11af utilizing a TV white space (TVWS) band and IEEE 802.11ah utilizing a 900 MHz band. These protocols aim at extending an extended range Wi-Fi service, as well as a smart grid, a wide area sensor network. Also, an existing WLAN medium access control (MAC) technology has a problem that an initial link setup time is too long. In order to solve this problem to allow a STA to quickly access an access point (AP), IEEE 802.11ai standardization has been actively ongoing.
IEEE 802.11ai is a MAC technology handling a fast authentication procedure to remarkably reduce an initial set-up and association time of a WLAN, which started standardization as a formal task group in January 2011. In order to allow for a fast access procedure, IEEE 802.11ai has discussed procedure simplification in regions such as AP discovery, network discovery, time synchronization function (TSF) synchronization, authentication & association, procedure merging with a higher layer, and the like. Among them, ideas such as procedure merging utilizing piggyback of dynamic host configuration protocol (DHCP), optimization of full extensible authentication protocol (EAP) using concurrent IP, effective selective AP scanning, and the like, have been actively discussed.